Electromagnet



July. 15 1924. 1,501,787

' H. LACY ELECTROMAGNET Filed Nov. 5, 1921 fl z Patented July 15, 1924.

HOWARD LACY, F SURBITON, ENGLAND.

ELECTROMAGNET.

Application filed November 3, 1921.

To all whom z't may concern:

Be it known that I, Hownnn LACY, subject of the King of Great Britain, residing at Haycroft, Hook, Surbiton, Surrey, England, have invented certain new and useful Improvements in Electromagnets, of which the following is a specification.

This invention relates to electro-magnets of the type referred to in United States Letters Patent No. 928,136, which discloses a construction wherein an electro-magnet is formed by winding about a. core (composed of a bundle of soft iron wires clamped at the ends by washers) superimposed groups of even numbers of layers of wire whereof the diameter of the wire composing each successive group diminishes progressively and the number of layers in each successive group increases in direct arithmetical pro gression from the core outwardly, insulating material being interposed between the core and the adjacent winding and between successive layers of the series, the direction of winding being reversed at the end of every second layer, and the free ends of the wire composing each group being brought out at the same end of the magnet for the purpose of being connected up in accordance with certain desired combinations.

The object of the present invention is to provide an improved form of winding which makes it possible to operate the electromagnet over a greater range of voltage and amperage than was formerly possible.

According to this invention an electromagnet iswound with an even number of superimposed pairs of layers of wire where of the gauge of the wire composing each successive pair of layers diminishes progressively outwardly of the core and the direction of winding for each pair of layers is reversed, insulation being placed between successive layers, and the beginning and end of each wire is brought out at the tail end of the magnet.

Thus there may be two sizes, four sizes, six sizes, eight sizes and so on, each size comprising two layers and each two layers being oppositely wound.

be present invention therefore differs from the disclosures in the above mentioned prior patent in that the number of layers o1 each sized wire is now constant and, instead of a. wire being reversed upon itself at the end of every second layer the direction of Serial No. 512,608.

sulated from its adjacent layer before being wound thereon.

By way of example one construction of elect-ro-magnet is illustrated in the accompanying drawings, in which Figure 1 is a cross-section of one leg of a magnet embodying the invention and Figure 2 is a plan view, partially in section, of a portion of said leg.

A is the core which is composed of a bundle of soft iron wires having at each end a Washer or spreader B compressed thereon for the purpose of holding the wires firmly in position, and having also at each end a disc 0 of insulating material fitted thereover in order to support the windings; the diameter of each spreader B being twice the diameter of the core, as already provided for in prior United States Letters Patent No. 928,136.

The yoke, which is not illustrated in the drawings, should be equal in size in square inches to one half the length of the core, and should be equal in width to the diameter of the Spreaders B upon which said yoke is placed at the tail of the core. vB5

Having built up the core A and having attached the Spreaders and discs, the core is then thoroughl insulated.

A wire a 0 say No. 14 gauge is then wound upon core A in a clockwise direction and is continued until two layers have been completed, insulation being placed between each la er. The beginning (L1 and the end a? of the wire a are both brought out at the tail end of the magnet.

A wire Z), of say 15 gauge is then wound, in a counter-clockwise direction, upon the second layer of wire and is insulated from the latter, and when one layer of wire I) has been completed this is insulated and a second layer of the wire I), also wound counter-clockwise, is applied, the beginning 6 and the end 6 being brought out at the tail end of the magnet.

The outer layer of wire I) is insulated and a wire 0, of say No. 16 gauge, is wound thereon in a clockwise direction, insulation being applied when one layer has been completed, and a second layer of wire 0 is agaln wound in a clockwise direction; the begin- 11 wire f, of say ning c and the end 0 of wire 0 being brought out at the tail end of th magnet.

After insulating the outer layer of wire 0 a wire (L of say NO. 17 gauge, is then wound thereon in a counter-clockwise direction, two layers insulated from one another being applied, and the beginning 65 and the end (Z being both brought out at the tail end of the magnet.

Then follow two layers of a wire 0, of say No. 18 gauge, each wound in a clockwise direction,'with the beginning 6 and'the end 6 brought outat the tail end of the magnet, and finally, after insulating the outer layer of wire 0, there are applied two layers of a No. 19 gauge, each layer wound in a counter-clockwise direction, insulated from one another, and the beginning 7 and end f brought out in the same way as the beginnings and ends of the wires a, b, 0, d, and c. p

The sizes or gauges of wires already stated above set forth are merely given by way of example and other sizes may of course be employed, depending upon the voltage and purpose for which the electromagnet isv intended. Similarly, the number of different sized wires employed also depends upon th voltage and amperage and invariably increases in arithmetical progression.

WVith this form of (consisting of a pair of layers, both of which are wound in the same direction around the core.) functions with its next adjacent wire (correspondingly consisting of a pair of layers wound around the core in the opposite direction to the preceding pair), and the inductance, turn for turn, balances; but since successive wires decrease in size from the core outwardly, there is a progressively increasing surplus of ampere-turns per wire from the second wire outwardly. and therefore an increasing inductive effect, as the result of which with every combination of the wires, effective ampere-turns are available.

Ihavediscovered that this form of winding enables me to design a magnet for a given purpose from wires of considerably winding each wire smaller gauge than prescribed by standardized practice and as a result a great saving in the amount of copper used in the construction of a magnet is effected.

The inductance is weakest when all the different sized wires are connected in series and strongest when all are connected in multiple, all wires being always in circuit in every combination.

By bringing out the ends of each sized wire as described, various combinations of the diiferent sized wires of two layers each can be attained; and, by virtue of this new form of winding, a less restricted number of combinations can be effected than was the case in the. magnets described in the above-mentioned prior patent.

What I claim is 1. An electro-magnet of the type described, comprising a core and a winding composed of an even number of differently sized wires each wound in two layers in the same direction and with the direction of winding of successive wires reversed, said wires decreasing in size progressively in accordance with th ampere-turns required per wire, and insulation between all layers of the winding, whereby said wires are adapted to function in pairs to produce a variable inductance, tie value of which may be controlled by inter-connecting the wires to form different combinations.

2. An electro-magnet of the type described comprising a core, a winding, con sisting of an even number of differently sized. wires each wound in two layers both in the same direction, the winding of successive wires being reversed, said wires decreasing in diameter progressively outward and consisting of numbers of turns as the distance from the core increases, and insulation between the layers, the ends of said wires being adapted to be connected in various combinations for producing different valuations of induction in the core.

In testimony whereof I have hereunto set my hand.

How-Ann LACY.

progressively greater- 

